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SOLUTIONOFMOCKTEST
JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)
CONDUCTEDONDOUBTNUTAPP
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Q-1-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
At waterhas .Whatisthe
pHofpurewateratthistemperature?
(A)6.667
(B)
(C)
(D)
CORRECTANSWER:D
AttemptMockTestonDoubtnutApp
Q-2-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Thecompound(C)is:
(A)
(B)
(C)
(D)
CORRECTANSWER:C
SOLUTION:
NA
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Q-3-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
onreactionwith inaq.Solution
givesbluecolour.Theseareseparatedbya
semipermeablemembrane asshown.Dueto
osmosisthereis-
(A)bluecolourformationinside
(B)bluecolourformationinside
(C)bluecolourformationinbothofthesides
and
(D)nobluecolourformation
CORRECTANSWER:D
AttemptMockTestonDoubtnutApp
Q-4-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Medicinewhichisanantibioticis:
(A)ampicillin
(B)aspirin
(C)calmpose
(D)chloroquine
CORRECTANSWER:A
AttemptMockTestonDoubtnutApp
Q-5-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Agas atatmisbubbledthroughasolution
containingamixtureof and
at C.Ifthereductionpotentialorderis
,then:
(A)ClwilloxidiseFandnotBr
(B)ClwilloxidiseBrandnotF
(C)ClwilloxidisebothBrandF
(D)ClwillreducebothBrandF
CORRECTANSWER:B
AttemptMockTestonDoubtnutApp
Q-6-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Thefollowingstatementsrelatedtotheadsorptionof
gasesonasolidsurface.Identifytheincorrect
statementamongthem.
(A)Onadsorption,theresidualforcesonthe
surfaceareincreased
(B)Onadsorption,decreaseinsurfaceenergy
appearsasheat
(C)Entropyofadsorptionisnegative
(D)Enthalpyofadsorptionisnegative
CORRECTANSWER:A
AttemptMockTestonDoubtnutApp
Q-7-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
TheIUPACnameofthecompoundis:
(A)2-methyl-6-oxohex-3-enamide
(B)6-keto-2-methylhexanamide
(C)2-carbamoylhexanal
(D)2-carbamoylhex-3-enal
CORRECTANSWER:A
AttemptMockTestonDoubtnutApp
Q-8-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Anelectron,aprotonandanalphaparticlehave
kineticenergiesof16E,4EandErespectively.What
isthequantitativeorderoftheirdeBroglie
wavelengths?
(A)
(B)
(C)
(D)
CORRECTANSWER:A
AttemptMockTestonDoubtnutApp
Q-9-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
The -ketoacidonheatingundergoesdecarboxy-
lationeasily.
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Q-10-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Wehavetwomineralsofonemetal,firstissulphide
andsecondisoxide.Thenfindthecorrectstatement
regardingextractionofmetalfromthesetwo
minerals.
(A)Sulphidemineralisgoodchoicefor
extractionofmetal
(B)Oxidemineralisgoodchoiceforextractionof
metal
(C)Anyofthesetwomaybeore,dependsonthe
concentrationofthemetalintheminerals,
durabilityoftheprocessandotherrelevant
factors
(D)Alwayssulphidemineralwillbetheore
CORRECTANSWER:C
AttemptMockTestonDoubtnutApp
Q-11-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Thehormonewhichcontrolstheprocessofburning
offats,proteins,andcarbohydratesandliberates
energyinthebodyis:
(A)Thyroxine
(B)Adrenaline
(C)Insulin
(D)Cortisone
CORRECTANSWER:C
AttemptMockTestonDoubtnutApp
Q-12-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Inwhichofthefollowingreaction actsasa
reducingagents?
(D)
(A) and
(B) and
(C) and
(D) and
CORRECTANSWER:C
SOLUTION:
Reducingagentsmeansthatthecompounds
undergoesoxidation,i.e.,thecompoundloses
electrons.In(B)and(D), losseselectrons.
Hence,answeris(c).
AttemptMockTestonDoubtnutApp
Q-13-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Whichofthefollowingiserythroformandoptically
inactive
(A)
(B)
(C)
(D)
CORRECTANSWER:C
AttemptMockTestonDoubtnutApp
Q-14-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
0.5moleeachoftwoidealgases
and aretakeninacontainerand
expandedreversiblyandadiabatically,duringthis
processtemperatureofgaseousmixturedecreased
from350Kto250K.Find (incal/mol)forthe
process:
(A)
(B)
(C)
(D)Noneofthese
CORRECTANSWER:C
SOLUTION:
AttemptMockTestonDoubtnutApp
Q-15-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Inwhichofthefollowingspecies bondis
presentbut -ppi`bondisabsent?
(A)
(B)
(C)
(D)
CORRECTANSWER:D
SOLUTION:
AttemptMockTestonDoubtnutApp
Q-16-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Thesetofcompoundswhichdoesnotexist,is
(A)
(B)
(C)
(D)
CORRECTANSWER:A
SOLUTION:
(a).
Duetoinertpaireffect, convertsinto
ion,hence doesnotexist,
(b).
duetoinertpaireffect, ionconvertsinto
hence doesnotexist.
(c). doesnotexist,becauseofabsence
ofd-orbitalcontraction
AttemptMockTestonDoubtnutApp
Q-17-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Thestartingmaterialof is:
(A)Monochlortrifluroethylene
(B)Tetrafluoroethylene
(C)Vinylchloride
(D)Styrene
CORRECTANSWER:A
AttemptMockTestonDoubtnutApp
Q-18-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Forareaction products,theratelaw
expressionis
then
(A)
(B)
(C) mayormaynotbeequalto
(D)
CORRECTANSWER:C
SOLUTION:
Becauseorderofreactionisanexperimental
termstherefore,itmayormaynotbeequalto
AttemptMockTestonDoubtnutApp
Q-19-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Thegasmainlyresponsibleforglobalwarmingis:
(A)
(B)
(C)
(D)
CORRECTANSWER:A
AttemptMockTestonDoubtnutApp
Q-20-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Whichofthefollowingisbasic?
(A)
(B)
(C)
(D)
CORRECTANSWER:A
SOLUTION:
Acidicstrength:
.
Basicstrengthisreverse,so isbasic.
AttemptMockTestonDoubtnutApp
Q-21-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Findthetotalnumberofdiproticacidsamongthe
following:
CORRECTANSWER:5
SOLUTION:
Diproticacidsarethosewhichfurnishtwo
protonspermolecule.
(Monobasic)
Onlythosehydrogensarereplaceableformoxy-
acidsofphosphorusandsulphurwhichare
attachedtooxygen.
(Tribasic)
(Dibasic)
(Monobasic)
AttemptMockTestonDoubtnutApp
Q-22-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
FindthenumberofmoleculeshavingtwoLonepair
ofelectronsoncentralatom.
CORRECTANSWER:5
SOLUTION:
AttemptMockTestonDoubtnutApp
Q-23-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Amongthefollowingcompounds,thenumberoffood
preservativeis_____.
Propylgallate,butylatedhydroxylanisole,saccharin,
butylatedhydroxyltoluene,xylitol,p-hydroxybenzoic
acid,sodiumbenzoate
CORRECTANSWER:5
AttemptMockTestonDoubtnutApp
Q-24-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Whichofthefollowingcanactasambidentate
ligand?
CORRECTANSWER:3
SOLUTION:
ambidentate
AttemptMockTestonDoubtnutApp
Q-25-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
CHEMISTRY
Inabovebalancereaction,valueof willbe:
CORRECTANSWER:8
AttemptMockTestonDoubtnutApp
Q-26-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Iftheline beatangenttothehyperbola
,then isequalto
(A)
(B)
(C)
(D)noneofthese
CORRECTANSWER:C
SOLUTION:
Theequationofthehyperbolais
.
Theline touchesthishyperbola,if
[Using ]
+-16`
AttemptMockTestonDoubtnutApp
Q-27-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Thevalueof
,is
(A)1
(B)
(C)0
(D)noneofthese
CORRECTANSWER:C
SOLUTION:
Applying ,weget
AttemptMockTestonDoubtnutApp
Q-28-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Theequationofthecommontangenttotheparabolas
,is
(A)
(B)
(C)
(D)
CORRECTANSWER:B
SOLUTION:
Theequationofanytangentto is
Ifitisatangenttotheparabola ,then
theequation
Puttingthevalueofmin(i),weget
Thisistheequationofthecommontangent.
ALITERTheequationofanytangentto
is
wherem'
Ifittouchestheparabola ,thenwe
musthave
Substitutingthevalueofmin(i),weobtaintha
equationoftherequiredcommontangentas
AttemptMockTestonDoubtnutApp
Q-29-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Ifarealpolynomialofdegreensatisfiestherelation
(A)anontofunction
(B)anintofunction
(C)alwaysaonefunction
(D)alwaysamanyonefunction.
CORRECTANSWER:A
SOLUTION:
Letf(x)beapolynomialofdegreen.Then,
f'(x)andf''(x)arepolynomialofdegree(n-1)and
(n-2)respectively.
Clearly,f(x)beingapolynomialofdegree3,isan
ontofunctions.
AttemptMockTestonDoubtnutApp
Q-30-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Ifoneofthelinesof
isabisectoroftheanglebetweenthelinesxy=0,
thenmis
(A)1
(B)2
(C)
(D)
CORRECTANSWER:A
SOLUTION:
Clearly,linesgivenbyxy=0arex=0,y=0i.e.
thecoordinateaxesandtheirbisectorsare
Putting in
,weget
Hence,option(a)iscorrect.
AttemptMockTestonDoubtnutApp
Q-31-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
If ,thenxbelongsto
(A)
(B)
(C)
(D)R
CORRECTANSWER:C
AttemptMockTestonDoubtnutApp
Q-32-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Theprobabilityofamanhittingatargetis .Ifhe
fires,ntimessuchthattheprobabilityofhishitting
thetargetatleastonceisgreaterthan ,thenthe
valueofn,is
(A)3
(B)4
(C)5
(D)noneofthese
CORRECTANSWER:B
AttemptMockTestonDoubtnutApp
Q-33-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Theequation has
(A)norealrootsset
(B)exactlyonerealroot
(C)tworealroots
(D)infinitelymanyrealroots
CORRECTANSWER:B
AttemptMockTestonDoubtnutApp
Q-34-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Ifthelinesegmentjoining(2,3)and(-1,2)isdivided
internallyintheratio3:4bytheline ,
then =
(A)
(B)
(C)
(D)
CORRECTANSWER:A
AttemptMockTestonDoubtnutApp
Q-35-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Thecircle intersectstheline
attwodistinctpoints,if
(A)
(B)
(C)
(D)
CORRECTANSWER:D
SOLUTION:
Iftheline intersectsthecircle
attwodistinctpoints,thenLengthof
perpendicularfromcentre Radius
AttemptMockTestonDoubtnutApp
Q-36-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
In ,considertheplanes and
.Let beaplane,differentfrom
and whichpassesthroughtheintersectionof
and .Ifthedistanceofthepoint(0,1,0)andfrom
is1andthedistanceofapoint from is
2,thenwhichofthefollowingrelationsis(are)true?
(A)
(B)
(C)
(D)
CORRECTANSWER:D
SOLUTION:
Theplanepassingthroughtheintersectionof
planes and is
or ..i
Itisgiventhatthedistancesofthepoint
and fromiare1and2respectively.
and
and
and
and
or
AttemptMockTestonDoubtnutApp
Q-37-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Let and bethreenon-coplanarunitvectors
suchthattheanglebetweeneverypairofthemis
.If
,where and arescalars,thenthevalueof
,is
(A)
(B)
(C)
(D)
CORRECTANSWER:B
SOLUTION:
Wehave
Takingdotproductwith weobtain
..ii
Takingdotproductonbothsidesof(i)by ,we
get
................iii
Takingdotproductonbothsidesof(i)by we
get
Putting in(iii)weget Thus,we
obtain
AttemptMockTestonDoubtnutApp
Q-38-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Thevectors liesintheplaneofvectors and ,
whichthefollowingiscorrect.
(A)
(B)
(C)
(D)
CORRECTANSWER:A
AttemptMockTestonDoubtnutApp
Q-39-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Thedifferentialequationoffamilyofcircleswith
fixedradius5unitsandcentreontheliney=2,is
(A)
(B)
(C)
(D)
CORRECTANSWER:A
SOLUTION:
Let(a,2)bethecentreofthecircle,where'a'is
avariable.Then,theequationofthefamilyof
circlesis
Differentiatingw.r.tox,weget
Substitutingthisvalueof in(i),weget
astherequireddifferentialequation.
AttemptMockTestonDoubtnutApp
Q-40-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Thevalueof ,is
(A)
(B)
(C)
(D)noneofthese
CORRECTANSWER:B
SOLUTION:
AttemptMockTestonDoubtnutApp
Q-41-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
IfthetangentatapointP,withparametert,onthe
curve
meetsthecurveagainatQ,thenthecoordinatesofQ
are
(A)
(B)
(C)
(D)
CORRECTANSWER:A
SOLUTION:
Let beapointonthegiven
curve.
Now,
ThetangenttothecurveatPis
Thiswillpassthrough if
So,thecoordinatesofQare
AttemptMockTestonDoubtnutApp
Q-42-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
If ,then
(A)
(B)
(C)
(D)
CORRECTANSWER:B
AttemptMockTestonDoubtnutApp
Q-43-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Thesetofpointswherethefunction.
Where[.]denotesthegreatestintegerfunction,is
notdifferentiable,is
(A)
(B)
(C)
(D)
CORRECTANSWER:C
SOLUTION:
Wehave
Clearly,f(x)isdiscontinuousatx=0,1,2and3.
So,itisnotdifferentiableatthesepoints.
Atx=-1,wehave
So,itiscontinuousatx=-1
Also,(RHDatx=1)=-1(afinitenumber).
Therefore,f(x)isdifferentiableatx=-1
AttemptMockTestonDoubtnutApp
Q-44-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Letthefunction
bedefinedontheinterval[0,1].Theevenextension
off(x)totheinterval[0,1].Theevenextensionoff(x)
totheinterval[-1,1]is
(A)
(B)
(C)
(D)noneofthese
CORRECTANSWER:A
AttemptMockTestonDoubtnutApp
Q-45-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
If
(A)2
(B)1
(C)3
(D)4
CORRECTANSWER:D
AttemptMockTestonDoubtnutApp
Q-46-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Thedifferentialequationofallparabolaswhoseaxis
ofsymmetryisalongx-axisisoforder
CORRECTANSWER:2
SOLUTION:
Thegeneralequationofthesaidparabolasis
,wherea,barearbitraryconstants.
So,thedifferentialequationisoforder2.
AttemptMockTestonDoubtnutApp
Q-47-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Atpresent,afirmismanufacturing2000items.Itis
estimatedthatrateofchangeofproductionPwith
respecttoadditionalnumberofworkersxisgivenby
ifthefirmemploys25more
workers,thenthenewlevelfofproductionofitems
is
CORRECTANSWER:3500
AttemptMockTestonDoubtnutApp
Q-48-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Ifthelinejoiningthepoints(0,3)and(5,-2)isa
tangenttothecurve thenthevalueofC
is
CORRECTANSWER:4
AttemptMockTestonDoubtnutApp
Q-49-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
If
CORRECTANSWER:3
SOLUTION:
Weknowthattheminimumvalueof
whichisattainedatx=-1
AttemptMockTestonDoubtnutApp
Q-50-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
MATHS
Ina ,if
,then=c
CORRECTANSWER:2
SOLUTION:
Wehave,
AttemptMockTestonDoubtnutApp
Q-51-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
TwopointsPandQaremaintainedatthepotentials
of10Vand-4V,respectively.Theworkdonein
moving100electronsfromPtoQis:
(A)
(B)
(C)
(D)
CORRECTANSWER:C
SOLUTION:
AttemptMockTestonDoubtnutApp
Q-52-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
When5Vpotentialdifferenceisappliedacrossa
wireoflength0.1m,thedriftspeedofelectronsis
.Iftheelectrondensityinthewire
is ,theresistivityofthematerialisclose
to:
(A)
(B)
(C)
(D)
CORRECTANSWER:B
SOLUTION:
HereV=potentialdifference
l=lengthofwire
n=no.ofelectronsperunitvolumeof
conductor.
e=no.ofelectrons
Placingthevalueofaboveparametersweget
resistivity.
AttemptMockTestonDoubtnutApp
Q-53-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
InaYoung'sdoubleslitexperiment,12fringesare
observedtobeformedinacertainsegmentofthe
screenwhenlightofwavelength600nmisused.If
thewavelengthoflightischangedto400nm,
numberoffringesobservedinthesamesegmentof
thescreenisgivenby
(A)12
(B)18
(C)24
(D)30
CORRECTANSWER:B
SOLUTION:
,
AttemptMockTestonDoubtnutApp
Q-54-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Anucleuswithmassnumber initiallyatrest
emitsan particle Q
5.5MeV
alphaparticle`
(A)
(B)
(C)
(D)
CORRECTANSWER:B
SOLUTION:
Byconservationofmomentum,
rArrK_(2)=54K_(1) Also,K_(1)+K_(2)=5.5
MeV`(ii)
solveequation(i)and(ii)
AttemptMockTestonDoubtnutApp
Q-55-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Aparticleofmass isprojectedfromthegroundat
someanglewithhorizontal.Itshorizontalrangeis .
Atthehighestpointofitspathitbreaksintotwo
piecesofmasses and ,respectively,suchthat
thesmallermasscomestorest.Thelargermass
finallyfallsatadistance fromthepointof
projection,where isequalto
(A)
(B)
(C)
(D)
CORRECTANSWER:B
SOLUTION:
Applyconservationofmomentumathighest
point
.i
AttemptMockTestonDoubtnutApp
Q-56-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Auniformringofradius isgivenabackspinof
angularvelocity andthrownonahorizontal
roughsurfacewithvelocityofcentretobe .The
velocityofthecentreoftheringwhenitstartspure
rollingwillbe
(A)
(B)
(C)
(D)
CORRECTANSWER:B
SOLUTION:
Here
Atpurerolling
AttemptMockTestonDoubtnutApp
Q-57-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Inthearrangementasshown, ,densityof
liquidis anddensityofblock is .Thesystemis
releasedfromrestsothatblock movesupwhenin
liquidandmovesdownwhenoutofliquidwiththe
sameacceleration.Findthemassofblock .
SOLUTION:
Accelerationwhenblock intheliquid.
Accelerationwhenblock isoutsideofthe
liquid
Given weget
AttemptMockTestonDoubtnutApp
Q-58-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Waterrisestoaheightof inacapillarytube.If
thetubeistilted fromthevertical,waterwillrise
inthetubetoalengthof
(A)
(B)
(C)
(D)waterwillnotriseatall
CORRECTANSWER:A
SOLUTION:
Sincewaterriseofheightof inacapillary
Iftubeisat inthiscaseheightmustbeequal
to
AttemptMockTestonDoubtnutApp
Q-59-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Alargechargedmetalsheetisplacedinauniform
electricfield,perpendiculartotheelectricfieldlines.
Afterplacingthesheetintothefield,theelectricfield
ontheleftsideofthesheetis
andontherightitis .Thesheet
experiencesanetelectricforceof0.08N.Findthe
areaofonefaceofthesheet.Assumetheexternal
fieldtoremainconstantafterintroducingthelarge
sheet.Use
(A)
(B)
(C)
(D)none
CORRECTANSWER:A
SOLUTION:
Letexternalfieldbe andsurfacecharge
densityofsheet
be (includingbothsurfaces).So
Electricfieldduetosheet
.......(i)
........(ii)
From(i)and(ii),
and
Q-60-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
A bulbdesignedtooperateon istobe
connectedacrossa source.Findtheresistance
tobeputinseriessothatbulbconsumes only.
(A)
(B)
(C)
(D)
CORRECTANSWER:C
SOLUTION:
Resistanceofbulbis
Ifbulbconsumes ,thenpotential
differenceacrossthebulbshouldbe .So
.Andpotentialdifference
across .Soltbr
AttemptMockTestonDoubtnutApp
Q-61-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Twoplates,eachofareaA,areplacedparallelto
eachotheratadistanced.Oneplateisconnectedto
abatteryofemfEanditsnegativeisearthed.The
otherplateisalsoearthed.Thechargedrawnby
plateis
CORRECTANSWER:B
SOLUTION:
ThecircuitcanberedrawnasshowninFig.
Chargeoncapacitoris
Option(a),(c),and(d)areincorrect
AttemptMockTestonDoubtnutApp
Q-62-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Inanelectricfieldshowninfigure,three
equipotentialfigure,threeequipotentialsurfacesare
shown.Iffunctionareshown.Iffunctionofelectric
fieldis ,andgiventhat
,thenwehave
(A)
(B)
(C)
(D)datainsufficient
CORRECTANSWER:B
SOLUTION:
As increasingalong axis,samepotential
dropwilloccurforlesservaluesofdistance.
Hence .
AttemptMockTestonDoubtnutApp
Q-63-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Electricdipoleofmoment iskeptatapoint
(x,y)inanelectricfield .Find
AttemptMockTestonDoubtnutApp
Q-64-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Apointobjectisplacedatadistanceof25cmfroma
convexlensoffocallength20cm.Ifaglassslabof
thicknesstandrefractiveindex1.5isinserted
betweenthelensandtheobject,theimageisformed
atinfinity.Thethicknesstis
(A)10cm
(B)5cm
(C)20cm
(D)15cm
CORRECTANSWER:D
SOLUTION:
Imagewillbeformedatinfinityifobjectis
placedatfocusofthelens,i.e.,at20cmformthe
lens.Hence,
shift
or or
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Q-65-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
TheKEofthephotoelectronsisEwhentheincident
wavelengthis .TheKEbecomes2Ewhenthe
incidentwavelengthis .Theworkfunctionofthe
metalis
(A)
(B)
(C)
(D)
CORRECTANSWER:A
SOLUTION:
or
or
or
or
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Q-66-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Theradiusofthesecondorbitofanelectronin
hydrogenatomis .ThedeBrogliewavelength
associatedwiththiselectroninthisorbitwouldbe
(A)
(B)
(C)
(D)
CORRECTANSWER:A
SOLUTION:
or
deBrogliewavelength
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Q-67-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
ThewavelengthofthefirstlineofLymanseriesin
hydrogenatomis .Thewavelengthofthefirst
lineofLymanseriesfor timesionizedsodiumatom
willbeadded
(A)
(B)
(C)
(D)
CORRECTANSWER:D
SOLUTION:
Now,
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Q-68-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Half-lifeofaradioactivesubstance and are,
respectively, and .Initially,the
samplesof and haveequalnumberofnuclei.
After ,theratiooftheremainingnumberof
and nucleiis
(A)
(B)
(C)
(D)
CORRECTANSWER:C
SOLUTION:
Weknowthat
Q-69-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Twothindiscseachofmass andradius are
attachedasshowninfigure,tofromarigidbody.The
rotationalinertiaofthisbodyaboutanaxis
perpendiculartotheplaneofdisc andpassing
throughitscentreis:
CORRECTANSWER:D
SOLUTION:
.
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Q-70-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Findtheratioofelectricworkdoneinbringinga
charge from to andthatfrom to
inasphereofcharge distributed
uniformlythroughoutitsvolume.
(A)
(B)
(C)
(D)Noneofthese
CORRECTANSWER:A
SOLUTION:
Workdonebyelectricfield
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Q-71-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Acapacitorwithstoredenergy isconnected
withanidenticalcapacitorwithnoelectricfieldin
between.Findthetotalenergystoredinthetwo
capacitors.
CORRECTANSWER:2
SOLUTION:
Storedenergyofcapacitor
whentheyconnected,thechargeshared
Sothattheenergyshoulddividedthetotal
energystoredineachofthetwocapacitanceis2
J.
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Q-72-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Acylindricalvesselofheight500mmhasanorifice
(smallhole)atitsbottom.Theorificeisinitially
closedandwaterisfilledinituptoheightH.Now
thetopiscompletelysealedwithacapandthe
orificeatthebottomisopened.Somewatercomes
outfromtheorificeandthewaterlevelinthevessel
becomessteadywithheightofwatercolumnbeing
200mm.Findthefallinheight(inmm)ofwaterlevel
duetoopeningoftheorifice.
[Takeatmosphericpressure ,
densityofwater=1000kg//m^3 g=10m//s^2`.
Neglectanyeffectofsurfacetension.]
CORRECTANSWER:6
SOLUTION:
Initially,thepressureofaircolumnabovewater
is
andvolume ,whereAis
theareaofcross-sectionofthevessel.
Finally,thevolumeofaircolumnabovewateris
300A.If isthepressureofairthen
Asthetemperatureremainsconstant,according
toBoyle'slaw
Thefallofheightofwaterlevelduetothe
openingof
orifice
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Q-73-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
A massissuspendedfromawireofnegligible
mass.Thelengthofthewireis1manditscross
sectionalareis .Ifthemassispulleda
littleintheverticallydownwarddirectionand
released,itperformssimpleharmonicmotionof
angularfrequency .IftheYoung'smodulus
ofthematerialofthewireis ,the
valueofnis
CORRECTANSWER:4
SOLUTION:
Weknowthat (i)
Here
Comparingtheaboveequationwith we
get
(ii)
From(i)&(ii),
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Q-74-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Theactivityofafreshlypreparedradioactivesample
is disintergrationspersecond,whosemeanlife
is .Themassofanatomofthisradioisotopeis
.Themass(in )oftheradioactive
samplesis
CORRECTANSWER:1
SOLUTION:
at
massofsample
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Q-75-JEEMAINCRASHCOURSE-CRASHCOURSE(FULLTEST2)-
PHYSICS
Twomutuallyperpendicularinfinitewiresalongx-
axisandy-axiscarrychargedensities .The
electriclineofforceatPisalongtheline
,wherePisalsoapointlyingonthe
sameline.Find .
CORRECTANSWER:3
SOLUTION:
Netelectricfieldis
duetoverticalwire
I -direction
duetoverticalwireinx-direction
or or or
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